Set Jinja2's keep_trailing_newline=True in template_from_string.

Without this setting, the newline idempotence of scalar strings changes depending on whether
or not they contain any Jinja2 template blocks.
Merge branch 'devel' of https://github.com/leverich/ansible into leverich-devel
Load existing group_vars file for new group_by group

if it was not loaded yet, which happens if that group
didn't exist yet in the inventory.

fixes #8159
Merge branch 'leverich-devel' into devel
Merge pull request #8170 from sergevanginderachter/issue_8159

Load existing group_vars file for new group_by group